What about getting a low swingweight extended frame and cutting it down to 27, scrap the overgrip, string it with 17g Syn, and trim the bumper?

J

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Yeah, I thought of that, but I did the math on all the low-swingweight extended frames and found that after cutting down to 27" they would still be higher than 270. Thanks for the suggestion though. Chucking the bumper will probably be necessary, but I'll need stronger strings than 17g syngut to withstand the impact with this thing once I've added 60 grams at 3&9.

Yeah, I thought of that, but I did the math on all the low-swingweight extended frames and found that after cutting down to 27" they would still be higher than 270. Thanks for the suggestion though. Chucking the bumper will probably be necessary, but I'll need stronger strings than 17g syngut to withstand the impact with this thing once I've added 60 grams at 3&9.

Well, in a recent study the TW Professor found that balls that impact below the longitudinal center of the stringbed have much more spin on them than balls that hit the center. Conversely, balls that hit above center have less spin. This has implications for shot to shot consistency, as the variable amount of spin produced will change the trajectory of the shot, and therefore will change where it lands.

On off-center shots we already lose a lot of speed, about 8-9 mph for shots 2 inches to either side of center, so add largely uncontrollable spin variability to that and you can see that hitting off center not only results in weaker shots but introduces a random wildness to these shots, as we can't really control if we hit above or below center when we miss the center. That we're at all accurate under these circumstances seems miraculous. :wink:

But the TW Professor found that adding 100 grams at 3&9 completely reversed this, instead of more spin below center you get roughly the same amount of spin as in the center, and if you hit above center you actually get more spin than the other locations. So everything flips around. If this effect is linearly dependent on how much weight you add, 60 grams added at 3&9 should make center impacts and above and below center impacts all the same in terms of spin. Also, all that mass at 3&9 will increase the twistweight so much that you will also lose much less speed on off-center impacts. It would pretty much be the ultimate control stick. So that's the little project. I just don't want to wreck my shoulder with too much swingweight

Well, in a recent study the TW Professor found that balls that impact below the longitudinal center of the stringbed have much more spin on them than balls that hit the center. Conversely, balls that hit above center have less spin. This has implications for shot to shot consistency, as the variable amount of spin produced will change the trajectory of the shot, and therefore will change where it lands.

On off-center shots we already lose a lot of speed, about 8-9 mph for shots 2 inches to either side of center, so add largely uncontrollable spin variability to that and you can see that hitting off center not only results in weaker shots but introduces a random wildness to these shots, as we can't really control if we hit above or below center when we miss the center. That we're at all accurate under these circumstances seems miraculous. :wink:

But the TW Professor found that adding 100 grams at 3&9 completely reversed this, instead of more spin below center you get roughly the same amount of spin as in the center, and if you hit above center you actually get more spin than the other locations. So everything flips around. If this effect is linearly dependent on how much weight you add, 60 grams added at 3&9 should make center impacts and above and below center impacts all the same in terms of spin. Also, all that mass at 3&9 will increase the twistweight so much that you will also lose much less speed on off-center impacts. It would pretty much be the ultimate control stick. So that's the little project. I just don't want to wreck my shoulder with too much swingweight

Well, in a recent study the TW Professor found that balls that impact below the longitudinal center of the stringbed have much more spin on them than balls that hit the center. Conversely, balls that hit above center have less spin. This has implications for shot to shot consistency, as the variable amount of spin produced will change the trajectory of the shot, and therefore will change where it lands.

On off-center shots we already lose a lot of speed, about 8-9 mph for shots 2 inches to either side of center, so add largely uncontrollable spin variability to that and you can see that hitting off center not only results in weaker shots but introduces a random wildness to these shots, as we can't really control if we hit above or below center when we miss the center. That we're at all accurate under these circumstances seems miraculous. :wink:

But the TW Professor found that adding 100 grams at 3&9 completely reversed this, instead of more spin below center you get roughly the same amount of spin as in the center, and if you hit above center you actually get more spin than the other locations. So everything flips around. If this effect is linearly dependent on how much weight you add, 60 grams added at 3&9 should make center impacts and above and below center impacts all the same in terms of spin. Also, all that mass at 3&9 will increase the twistweight so much that you will also lose much less speed on off-center impacts. It would pretty much be the ultimate control stick. So that's the little project. I just don't want to wreck my shoulder with too much swingweight

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Good stuff Corners!

In recent experiments with my PSGTs I found that adding weight to 3/9 and not adding much weight (or any) to 12 INCREASED spin.

And if I deleted too much weight from 3/9 spin actually DECREASED. It's as if the head lacked enough mass to keep the ball deep on the strings.

So I discovered a sweet spot for myself for weight at 3/9 and 12: enough to enhance spin (maybe through dwell time? I dunno) but not too much weight to reduce racquet head speed thereby also reducing spin.

I know this is probably contrary to conventional wisdom about polarized vs non-polarized frames but I can't ague with the results I saw on court, especially on serve. When I stripped all the extra head lead on a PSGT spin suffered terribly. Then I added weight until I felt like speed might suffer and, voila! Incredible, brain-dead accessible spin.

The problem with zero weight at 12 was lack of punch on serve. Needed at least some at 12 for pace.

In recent experiments with my PSGTs I found that adding weight to 3/9 and not adding much weight (or any) to 12 INCREASED spin.

And if I deleted too much weight from 3/9 spin actually DECREASED. It's as if the head lacked enough mass to keep the ball deep on the strings.

So I discovered a sweet spot for myself for weight at 3/9 and 12: enough to enhance spin (maybe through dwell time? I dunno) but not too much weight to reduce racquet head speed thereby also reducing spin.

I know this is probably contrary to conventional wisdom about polarized vs non-polarized frames but I can't ague with the results I saw on court, especially on serve. When I stripped all the extra head lead on a PSGT spin suffered terribly. Then I added weight until I felt like speed might suffer and, voila! Incredible, brain-dead accessible spin.

The problem with zero weight at 12 was lack of punch on serve. Needed at least some at 12 for pace.

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Hey Tim, yeah you were probably getting the general benefits of added mass to spin - longer dwell time, more tangential string movement, more ball flattening. Mass at 12 livens the upper hoop which seems to help me with serve too. I hit higher on the stringbed on groundies too, so I've never been much of a 3&9 man, I like 10 to 2. But I'm curious how 60 grams at 3&9 would play. I just need to keep the swingweight under 350 or I know it will just collect dust. But it would be kind of funny if, with all that lead on, my groundies are super-accurate and spinny but my serve sucks due to lack of lead at 12 :lol:

From the racquet finder I'm seeing the 27" Head Airflow 7 ( sw 265 ) a few digits lower than the BLX Tour Lite, at 276. From the looks of it, if you are ever trapped in a snow storm it just might save your life.

Just in case you missed it, Trav went down a similar path, around 2006 or so. He was able to get a POG Long Body down to sw 276 - 280 range by cutting the pallet down. While those digits don't line up for what you've got in mind, it might make for interesting reading.

Well, in a recent study the TW Professor found that balls that impact below the longitudinal center of the stringbed have much more spin on them than balls that hit the center. Conversely, balls that hit above center have less spin. This has implications for shot to shot consistency, as the variable amount of spin produced will change the trajectory of the shot, and therefore will change where it lands.

On off-center shots we already lose a lot of speed, about 8-9 mph for shots 2 inches to either side of center, so add largely uncontrollable spin variability to that and you can see that hitting off center not only results in weaker shots but introduces a random wildness to these shots, as we can't really control if we hit above or below center when we miss the center. That we're at all accurate under these circumstances seems miraculous. :wink:

But the TW Professor found that adding 100 grams at 3&9 completely reversed this, instead of more spin below center you get roughly the same amount of spin as in the center, and if you hit above center you actually get more spin than the other locations. So everything flips around. If this effect is linearly dependent on how much weight you add, 60 grams added at 3&9 should make center impacts and above and below center impacts all the same in terms of spin. Also, all that mass at 3&9 will increase the twistweight so much that you will also lose much less speed on off-center impacts. It would pretty much be the ultimate control stick. So that's the little project. I just don't want to wreck my shoulder with too much swingweight

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Hi Corners,

The lowest swingweight racket I experimented with was a Voelkl Quantum Energy (listed SW 285 (I believe strung)). I added about 25 grams total at the sides and it was defenitely very stable and launchangle predictable. It would be interesting to know what your findings will be regarding the spin production with type of set-up.

From the racquet finder I'm seeing the 27" Head Airflow 7 ( sw 265 ) a few digits lower than the BLX Tour Lite, at 276. From the looks of it, if you are ever trapped in a snow storm it just might save your life.

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I'd better get a pair.

Just in case you missed it, Trav went down a similar path, around 2006 or so. He was able to get a POG Long Body down to sw 276 - 280 range by cutting the pallet down. While those digits don't line up for what you've got in mind, it might make for interesting reading.

Thanks Jack, yeah, gotta give props to Trav - he's the inspiration for all extreme customizations at my place. I really wish the Longbody would come down to 250 after cutting, then I'd be in business, as the POG is solid. But unlike Trav, I can't handle 370 SW sticks. Gotta find me something even less substantial as a starting point!

The lowest swingweight racket I experimented with was a Voelkl Quantum Energy (listed SW 285 (I believe strung)). I added about 25 grams total at the sides and it was defenitely very stable and launchangle predictable. It would be interesting to know what your findings will be regarding the spin production with type of set-up.

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Hi John, Thanks for suggesting the Energy. But a Google search turns up lots of German pages, and TW doesn't have that model in their archives. Do you think it was a Euro-only release? Do you remember the flex?

I'll definitely post a review of the Perimeter Weighted Super, if I find a stock frame with low enough SW. Right now it's looking like BLX Tour Lite or Quantum Energy, both sans bumper, are the leading candidates.

It seems that there's gotta be a pro stock with a base swingweight lower than those two, but I don't know.

Hi John, Thanks for suggesting the Energy. But a Google search turns up lots of German pages, and TW doesn't have that model in their archives. Do you think it was a Euro-only release? Do you remember the flex?

I'll definitely post a review of the Perimeter Weighted Super, if I find a stock frame with low enough SW. Right now it's looking like BLX Tour Lite or Quantum Energy, both sans bumper, are the leading candidates.

It seems that there's gotta be a pro stock with a base swingweight lower than those two, but I don't know.

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I am not sure about the origin. Probably European. The flex feels about mid sixty. I believe that the scorcher was similar spec-wise. I think of the current rackets, the Team Speed Orange or Green seem to have the same mold as the Energy and are not far of spec-wise.

I am not sure about the origin. Probably European. The flex feels about mid sixty. I believe that the scorcher was similar spec-wise. I think of the current rackets, the Team Speed Orange or Green seem to have the same mold as the Energy and are not far of spec-wise.

Changing strings, adding and subtracting a bit of lead here and there, that's all fine. But when you get to the point where you're doing math to find the proper MgR/I or something along those lines, I think you've gone too far.

Well, in a recent study the TW Professor found that balls that impact below the longitudinal center of the stringbed have much more spin on them than balls that hit the center. Conversely, balls that hit above center have less spin. This has implications for shot to shot consistency, as the variable amount of spin produced will change the trajectory of the shot, and therefore will change where it lands.

On off-center shots we already lose a lot of speed, about 8-9 mph for shots 2 inches to either side of center, so add largely uncontrollable spin variability to that and you can see that hitting off center not only results in weaker shots but introduces a random wildness to these shots, as we can't really control if we hit above or below center when we miss the center. That we're at all accurate under these circumstances seems miraculous. :wink:

But the TW Professor found that adding 100 grams at 3&9 completely reversed this, instead of more spin below center you get roughly the same amount of spin as in the center, and if you hit above center you actually get more spin than the other locations. So everything flips around. If this effect is linearly dependent on how much weight you add, 60 grams added at 3&9 should make center impacts and above and below center impacts all the same in terms of spin. Also, all that mass at 3&9 will increase the twistweight so much that you will also lose much less speed on off-center impacts. It would pretty much be the ultimate control stick. So that's the little project. I just don't want to wreck my shoulder with too much swingweight

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Why? Why ask why?

To my simple mind, the is like saying the ball will rebound the same off a steel wall so I want to turn my racket head into a steel wall so it shows no variance in response. My view is you don't want to do this.

If you add 60 g at 3/9, that will increase SW about 90 g - that's a lot.

It will also be enormously HH unless you counter with roughly 60G in the handle area. If you counter weight the handle, you will have added about 4 oz to the racket. If you leave it that HH, I expect it would take some time getting used to and god knows what it will do to your swing mechanics.

Dr Frank-en-stein has gone mad.

How about adding a little weight at 3 and 9 to increase twist weight and work hard to hit it near the center with a slightly closed racket face at impact.

is headsize a factor in this? would you have to add 60g if it was a 90" inch stick instead of a 100" stick?

i know you want to experiment, but i can't stand head heavy sticks. i feel i have less control over the head.

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Well, the experiment I'm working off of used a 105. This effect of equalizing spin across the stringbed by adding lots of mass at 3&9 added that mass to a 105. This effect must, to some rather large degree, rely on increasing twistweigtht to ridiculous levels. Because mass added at 3&9 far from the central axis boosts twistweight more than mass added a lesser distance, I'd like to try this with something at least 100 square inches. If it works as an experiment I'd be looking to try it in smaller headsizes too. The problem is that mids simply don't come with such low stock swingweights.

To my simple mind, the is like saying the ball will rebound the same off a steel wall so I want to turn my racket head into a steel wall so it shows no variance in response. My view is you don't want to do this.

If you add 60 g at 3/9, that will increase SW about 90 g - that's a lot.

It will also be enormously HH unless you counter with roughly 60G in the handle area. If you counter weight the handle, you will have added about 4 oz to the racket. If you leave it that HH, I expect it would take some time getting used to and god knows what it will do to your swing mechanics.

Dr Frank-en-stein has gone mad.

How about adding a little weight at 3 and 9 to increase twist weight and work hard to hit it near the center with a slightly closed racket face at impact.

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Don't worry dear friend, I have all those bases covered. Just need to find the right platform frame. In general, some people don't seem to have the spirit for experimentation. That's OK too.

Have you found a good platform, Corners?
Looking forward to your experience with it after customization!

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Hi John, my fine friends at TT have suggested two or frames that might work. Hoping something strangely ideal might be suggested soon, otherwise I'll press ahead with one of these candidates. Jolly was going to check with a pro stock expert....kinda waiting on that too.

The TW Professor didn't add 100 g to a frame that weighed 0. It was 100 g plus whatever the hitting weight (effective mass at a particular point) of the particular racket used in the test. So, the magic number isn't 100 at 3&9; it's whatever the final total hitting weight of the racket was at 3&9 after the 100 g was added.

Instead of trying to find a frame with a SW of 260 so that you can add the 60 g that you have your mind set on, maybe you need to calculate the ideal hitting weight that you are trying to achieve at 3&9. Then, once you know your ideal hitting weight in that location, you can use the hitting weight numbers that the TW Professor has already compiled to find frames that can let you reach your goal with a different amount of added lead.

For example, you might find a frame with a SW of 300 that does exactly what you want when you add 30 g at 3&9 without pushing you out of your comfort zone in terms of overall specs. Or, you might find a frame with an even higher swingweight that works with only 15 g added.

The TW Professor didn't add 100 g to a frame that weighed 0. It was 100 g plus whatever the hitting weight (effective mass at a particular point) of the particular racket used in the test. So, the magic number isn't 100 at 3&9; it's whatever the final total hitting weight of the racket was at 3&9 after the 100 g was added.

Instead of trying to find a frame with a SW of 260 so that you can add the 60 g that you have your mind set on, maybe you need to calculate the ideal hitting weight that you are trying to achieve at 3&9. Then, once you know your ideal hitting weight in that location, you can use the hitting weight numbers that the TW Professor has already compiled to find frames that can let you reach your goal with a different amount of added lead.

For example, you might find a frame with a SW of 300 that does exactly what you want when you add 30 g at 3&9 without pushing you out of your comfort zone in terms of overall specs. Or, you might find a frame with an even higher swingweight that works with only 15 g added.

This might make it easier to find a platform to get started on.

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Do you mean a racket with a very high twistweight/swingweight ratio? Am I correct?

Do you mean a racket with a very high twistweight/swingweight ratio? Am I correct?

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That's ideal for this particular expirement, but it might be just as difficult to find. However, a fairly moderate swingweight/twistweight might work if the overall mass is low enough to allow Corners to get to the ideal setup without going over the limit in overall specs.

The main thing is to focus on the real goal, which is the final twistweight/hitting weight at 3&9 rather than a specific amount of lead tape.

That's ideal for this particular expirement, but it might be just as difficult to find. However, a fairly moderate swingweight/twistweight might work if the overall mass is low enough to allow Corners to get to the ideal setup without going over the limit in overall specs.

The main thing is to focus on the real goal, which is the final twistweight/hitting weight at 3&9 rather than a specific amount of lead tape.

The TW Professor didn't add 100 g to a frame that weighed 0. It was 100 g plus whatever the hitting weight (effective mass at a particular point) of the particular racket used in the test. So, the magic number isn't 100 at 3&9; it's whatever the final total hitting weight of the racket was at 3&9 after the 100 g was added.

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If you read the paper you'll see that 100 was grams added at 3&9 to an Exo3 Red 105. The addition of this amount of mass effectively reversed the spin gradient from high (toward the sky when striking a groundy) to low (toward the ground) in the stringbed. Stock, this racquet produced much more spin on low impacts than in the center of the strings, and much less spin on high impacts than in the center. We can assume that all stock racquets share this relationship. By adding 100 grams of mass at 3&9 high impacts became more spin-friendly than in the center and low impacts became less spin friendly than the center. So the relationship observed in the stock condition was reversed.

But reversing this relationship is not the goal. Equalizing the spin production so that the stringbed produces the same amount of spin on high, low and central impacts is the goal. Adding 100 grams does not achieve that goal. The TW Professor mused that, if the addition of mass at 3&9 effectively reverses the relationship in a linear way, there may be an amount of mass that one could add that would achieve this goal. Some simple calculations showed that adding about 60 grams of mass should do this, assuming there is such a linear relationship. For the sake of experiment, I'm willing to run with this assumption.

Instead of trying to find a frame with a SW of 260 so that you can add the 60 g that you have your mind set on, maybe you need to calculate the ideal hitting weight that you are trying to achieve at 3&9. Then, once you know your ideal hitting weight in that location, you can use the hitting weight numbers that the TW Professor has already compiled to find frames that can let you reach your goal with a different amount of added lead.

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It would be tempting to assume that the greater hittingweight of added mass at 3&9 is responsible for the altered spin production seen in TWU's experiments with adding lots of mass. But it is not at all clear that hitting weight is the crucial factor here.

In the paper, six physical effects or phenomena were linked to the altered spin production seen at high and low impacts with and without added mass:

Increasing hittingweight will definitely have a big impact on numbers 5 and 6 on this list. But the relationship of hittingweight and effects 1-4 on the list is not at all clear.

On the other hand, increasing twistweight will almost certainly alter the rotation effect (#2 on the list) and short-side effects (#1), and the reversal in the spin-gradient from low to high seen in the experiment might be in large, or even most, part due to increasing twistweight by a huge amount because it is likely that these effects are those most amenable to modulation by the addition of mass. Adding those 100 grams to the Exo3 Red 105 pushed the twistweight to around 32.7. The greatest twistweight amongst racquets currently produced is about 21 (Wilson K4 OS), so we're definitely in uncharted territory here. Adding 60 grams at 3&9 to the Exo3 Red would bump the swingweight to around 24. So why not just add a couple grams at 3&9 to a K4 OS and call it a day?

It would be tempting to attribute the results described in the paper to measures that we are familiar with and understand well, like hittingweight and twistweight. But there are several more effects on the above list that are not often considered in conventional racquet customization work using relatively small amounts of mass. The bending effects documented in the paper, for example, are not something that people usually think about when adding a little lead to a racquet. Yes, I could use the the above twistweight number and calculate the hittingweight that would result from the addition of 60 grams at 3&9, and then attempt to target both those numbers. But would that achieve the goal?

Remember that the TWU experiments also included the addition of 100 grams of mass at 1&11. This would have increased the hittingweight much, much more than the addition of that mass at 3&9. So if we focus on a target hittingweight we would only need to add maybe 20 or 30 grams at 1&11 to hit that target. But, the addition of 100 grams at 1&11 did not produce the same effect on spin production at various impact locations as did mass at 3&9. Adding mass at 1&11 intensified the result observed in the stock condition - spin production was already greatest on low impacts and adding mass at 1&11 made this even more pronounced. This would suggest that increasing twistweight, not hittingweight, is most important to reverse the spin gradient observed in stock racquets.

And this is what the paper, at least hesitantly, concludes by noting that the short-side and rotation effects (numbers 1 & 2 on the list) are most responsible for the differences in spin production seen in high and low impacts. Increasing twistweight to around 24 could then, be a worthy goal. It's interesting to note that the short-side effect would be reduced using an oversize frame like the K4 112, because off-center impacts would be further from the frame than they would be in a midplus and even more so than with a mid. This suggests that, at a given twistweight, the difference in spin production for high and low impacts would be less with an oversize than with a midplus. A mid would be the worst. Also, since oversize frames naturally have greater twistweights, because any mass added or existing on the periphery of the frame is located further from the longitudinal axis, you'd have to add less mass to an oversize to achieve the goal of equalizing spin production across the stringbed. Conversely, you may have to add even more mass, perhaps much more, to achieve this goal with a mid. In fact, it could be that the K4 112 achieves the goal in stock form with it's twistweight of 22. But I'm not playing with that ugly thing!

Anyway, yes, it would be tempting to focus only increasing twistweight to a particular target, and in this case that target would be about 24. And in essence that's what I'm doing. What's the best location to add mass to increase twistweight the most while increasing hittingweight the least? At the frame's widest point - at 3&9. So I'm trying to find a frame with a very low swingweight so that I can add 60 grams at 3&9. The good news is that even a very light, low-swingweight frame like those kindly suggested so far have stock swingweights pretty close or only a little less than the Exo3 Red. Whew!

To those who have suggested that I should come down to earth and who have kindly pointed out that adding even modest amounts of mass at 3&9 changes the performance of a racquet: Thanks, you're right. But I'm not looking for performance enhancement; I'm looking to create the ultimate control racquet. LOL

The bummer, though, is that even if I do achieve the objective of making spin production uniform for all impacts across the racquet face from 3 to center to 9, I probably won't even know it. Times like these I wish I had a spin measurement rig in the basement.

If you read the paper you'll see that 100 was grams added at 3&9 to an Exo3 Red 105.

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Thanks for the follow-up. I didn't see the original paper, so I didn't know if the 100 g was a specific amount for a specific frame or just intentional overkill guaranteed to cause reversal in any racket (like saying a 5-lb brick will squash any grape).

The more I think about the problem, the more I suspect that what you're really looking for is a particular distribution of mass in terms of the ratio of mass in the upper, middle, and lower hoop. That is, if you have a frame with x% of the mass in the upper third of the hoop, y% in the middle third, and z% in the lower third, you'll get that consistent spin potential across the whole string bed regardless of the overall specs.

The difficult part is finding the exact values for x, y, and z, which will probably vary a bit frame by frame given differences in head shapes, flex patterns, and string spacing. If I were in your shoes, I'd start with the Exo3 Red and see if that 60 g really does give you the consistent spin potential that you're looking for (forget overall specs and personal preferences for the moment). You might find that that necessary modifications are more complicated and the results are difficult to verify.

But, if you do end up finding a way to verify the results and get what you're looking for, then you can start searching for other frames that will give you the overall specs you like after you've modified them to get that consistent string bed.

Basically, test the feasibility first on a well-known subject and then start looking for more ideal candidates later.

Thanks for the follow-up. I didn't see the original paper, so I didn't know if the 100 g was a specific amount for a specific frame or just intentional overkill guaranteed to cause reversal in any racket (like saying a 5-lb brick will squash any grape).

The more I think about the problem, the more I suspect that what you're really looking for is a particular distribution of mass in terms of the ratio of mass in the upper, middle, and lower hoop. That is, if you have a frame with x% of the mass in the upper third of the hoop, y% in the middle third, and z% in the lower third, you'll get that consistent spin potential across the whole string bed regardless of the overall specs.

The difficult part is finding the exact values for x, y, and z, which will probably vary a bit frame by frame given differences in head shapes, flex patterns, and string spacing. If I were in your shoes, I'd start with the Exo3 Red and see if that 60 g really does give you the consistent spin potential that you're looking for (forget overall specs and personal preferences for the moment). You might find that that necessary modifications are more complicated and the results are difficult to verify.

But, if you do end up finding a way to verify the results and get what you're looking for, then you can start searching for other frames that will give you the overall specs you like after you've modified them to get that consistent string bed.

Basically, test the feasibility first on a well-known subject and then start looking for more ideal candidates later.

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Thanks. But I think the issue here is not the distribution of mass from the top to the middle to the bottom of the stringbed. Trying to create a power gradient from top to bottom is a worthy goal because in theory it should be possible to setup a racquet so that a shot struck near the throat, a shot struck near the center and shot struck near the tip all rebound at the same speed. This would definitely improve control, because with stock racquets there is significant variation in shot speeds rebounding from different locations.

But I think it's pretty clear from the paper that two effects dominate the observed difference in spin generation between high (toward the sky) and low (toward the ground) impacts: the rotation effect and the short-side effect. If hittingweight, or the hittingweight gradient from throat to tip, were the critical factor, then the 100 grams added at 11&1 should have reversed this gradient, as 100 grams added to those locations would have bumped the swingweight by about 250 units. Adding 100 grams at 3&9 "only" increases swingweight by 200 units. But the relationship is reversed in terms of twistweight. Those grams at 3&9 increase the twistweight by about 12 units, while adding at 1&11 would only increase it by about 7 units. I think it's pretty clear that the reason why mass added at 3&9 worked to reverse the spin difference is because of the twistweight increase, which makes sense if you carefully read the descriptions of the rotation and short-side effects. Looking at the experimental results, it appears that adding mass at 11&1 would work too, but you'd have to add even more mass, like maybe 150 grams, which takes me far away from the secondary goal of keeping swingweight at a swingable level.

This is why I don't think it matters which frame I start with, as long as it has a twistweight of 11 or more, stock. Increasing swingweight, and thereby increasing hittingweight, should increase spin at all impact locations, but shouldn't change the observed spin gradient that much, if at all. So I'm not too concerned about the stock or final swingweight. (I might be wrong about this, however.)

In addition, the experiments in the paper provide a basis for further experimentation. It would have been best if the TW Professor had tried 60 grams and confirmed his hunch; but, his results with 100 grams certainly light the way towards trying 60 grams at home. Going in another direction entirely would, in my opinion, require a controlled spin testing rig like he has, which I haven't got. So I'll restrict my wild racquet ramblings to the path already slightly tamped down.

Unfortunately, all that mass concentrated at 3&9 will not equalize the throat to tip power gradient. But that's another problem, and one that Travlerjam has solved, I believe, by concentrating mass in the entire top half of the hoop, from 3 all the way round to 9. This is what Head has done too with their new Graphene Speed Pro, at least that's what their marketing says.

This got me inspired.
I just did an experiment with a Pure Storm Ltd.
I put two weights of 45 grams at the sides of the head and moved both up and down until I was satisfied with a constant launchangle when the tennisballs were hit across the face from 3 to 9. The most ideal spot seemed to be at 4 and 8. I know I varied not only twistweight but also swingweight and balance, but during play I also varied grip position up and down regardless of the present swingweight and balance.
The interesting part is that I tried to hit with constant rackethead speed and all over the racketface from 3 to 9 and with the weights attached at 4 and 8, the launchangle, speed and depth were pretty constant, which makes me believe that the spinrate also had to be pretty much the same. Whether a 425 grams racket is really playable is another question

This got me inspired.
I just did an experiment with a Pure Storm Ltd.
I put two weights of 45 grams at the sides of the head and moved both up and down until I was satisfied with a constant launchangle when the tennisballs were hit across the face from 3 to 9. The most ideal spot seemed to be at 4 and 8. I know I varied not only twistweight but also swingweight and balance, but during play I also varied grip position up and down regardless of the present swingweight and balance.
The interesting part is that I tried to hit with constant rackethead speed and all over the racketface from 3 to 9 and with the weights attached at 4 and 8, the launchangle, speed and depth were pretty constant, which makes me believe that the spinrate also had to be pretty much the same. Whether a 425 grams racket is really playable is another question

Really looking forward to your experience, Corners.

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Awesome John. What did you use for an easily movable 45g lump?

I wonder if you found 4&8 to equalize spin the most because of the headshape of the PSL, which kind of has a Volkl headshape, wider at 4&8 than most other frames. The only negative with mass at 4&8 is that it will tend to make the frame more powerful in the lower hoop, where it is already most powerful in stock form. I have always favored mass at 10&2 or higher as this will tend to equalize the power gradient of the frame and provide more pop on serve (which I tend to hit nearer the tip), in particular. But the positive of 4&8 is that it will raise the swingweight by a lesser amount that at 3&9 or higher.

It might take me awhile to get my experiment going as I'm taking my time in choosing the right platform frame, of which I'd like to get two so that I can make on-court comparisons. But thanks for the encouragement.

I wonder if you found 4&8 to equalize spin the most because of the headshape of the PSL, which kind of has a Volkl headshape, wider at 4&8 than most other frames. The only negative with mass at 4&8 is that it will tend to make the frame more powerful in the lower hoop, where it is already most powerful in stock form. I have always favored mass at 10&2 or higher as this will tend to equalize the power gradient of the frame and provide more pop on serve (which I tend to hit nearer the tip), in particular. But the positive of 4&8 is that it will raise the swingweight by a lesser amount that at 3&9 or higher.

It might take me awhile to get my experiment going as I'm taking my time in choosing the right platform frame, of which I'd like to get two so that I can make on-court comparisons. But thanks for the encouragement.

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I used two metal cycling cleats attached with strong, small width tape. So that the tape fits between the strings, around the frame. I moved both up and down by feel. I was worried if I put it to 10 and 2, the swingweight would be too high, but I might do that tomorrow, just to check whether it alters anything unexpected.

Could you, BTW, maybe explain to me what the reasoning is for wanting the upper part of head to be more powerful? I would say that in a normal groundstoke, the higher rackettipspeed would make up for that. Or is that also a matter of finding the right massgradiënt to even things out?